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Thread: Need help backfiring after bumping it to 13 lbs.

  1. #1
    Advanced Tuner =fast='s Avatar
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    Need help backfiring after bumping it to 13 lbs.

    Truck was running good at WOT I was bumping the boost and after 13lbs at WOT it start like having a backfire and airfuel looks good around 12.0 I don?t know if it wants more leaner. Change spark plugs and doing the same thing. What AFR are ya running on around 15 lbs??

    Truck it?s a 5.3, boost cam 76mm turbo, LT4 fuel system with external fuel pump, e85 on meth.

  2. #2
    Senior Tuner Higgs Boson's Avatar
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    so you are having combustion occur in the intake manifold (backfire) with a direct injection fuel system?

    or do you mean it sounds like it is breaking up at WOT?

    do you have a log and a tune to post for analysis?

  3. #3
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    You probably just need to gap the plugs tighter. What gap are you running?

  4. #4
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    What spark plugs? And you mean the exhaust is firing? I have a truck 5.3L 76mm and been running 15.5psi all week. I'm at 12.0afr stock fuel. not popping or issues.

  5. #5
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    Quote Originally Posted by Higgs Boson View Post
    so you are having combustion occur in the intake manifold (backfire) with a direct injection fuel system?

    or do you mean it sounds like it is breaking up at WOT?

    do you have a log and a tune to post for analysis?
    At WOT it sounds like it breaking, AFR looks good that’s why I’m like lost.

  6. #6
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    Quote Originally Posted by 1slow1500 View Post
    What spark plugs? And you mean the exhaust is firing? I have a truck 5.3L 76mm and been running 15.5psi all week. I'm at 12.0afr stock fuel. not popping or issues.

    I’m running the NGK LTR7-IX Iridium, would this plugs can be gap? I see the tip very sensitive.

  7. #7
    Senior Tuner Higgs Boson's Avatar
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    It's probably too rich. What is your injector pulse width? If you are running meth you might be running too much.

  8. #8
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    Quote Originally Posted by Higgs Boson View Post
    It's probably too rich. What is your injector pulse width? If you are running meth you might be running too much.
    I’m going to get time and do a log, I will try and make a video see if we can hear the breaking noise.

  9. #9
    Senior Tuner SultanHassanMasTuning's Avatar
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    if you raised boost, probably your need to check your plug gap
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